Impact of patch size on woody tree species richness and abundance in a tropical montane evergreen forest patches of south India

Abstract

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region, south India. We sampled woody trees (≥ 1 cm dbh) from 21 forest patches in the upper Nilgiri hills (> 2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs (≥ 1 to < 10 cm dbh) increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees (≥ 10 to < 30, ≥ 30 to < 60 and ≥ 60 cm dbh, respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance. Our findings suggest that with increasing forest patch area, tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns. Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area.

Keywords

Project funding: The work was supported by the National Natural Science Foundation of China (NSFC) through Young Scientist Grant No. 31200173, P. R. China and Center for Tropical Forest Science, Smithsonian Tropical Research Institute, Panama.

Notes

Acknowledgements

We are grateful to Dr. Jean-Philippe Puyravaud, Sigur Nature Trust who provided useful suggestions for experimental design and support for this study. We convey our deep gratitude to Prof. Dr. Qing-Jun Li and Dr. T. Muthukumar who provided logistic support and facilities for writing and revise this paper. We thank three anonymous referees especially Language Editor who greatly helped to improve the quality of manuscript and language. We thank Dr. Rama Chandra Prasad for his valuable help with map making and comments given on an earlier version of this manuscript. We thank Dr. Christos Mammides and Dr. V. S. Ramachandran for their valuable comments and language editing in earlier versions. We thank Mr. Hegde and staff of UNITEA Pvt. Ltd, the Tamil Nadu Forest Department and Electricity Board for logistic help and support. This publication was supported by the National Natural Science Foundation of China (NSFC) through Young Scientist Grant No. 31200173, P. R. China. This study was partially supported by a small grant from the Center for Tropical Forest Science, Smithsonian Tropical Research Institute and assistance from Dr. Egbert G. Leigh Jr.

Kumar S (1993) Survey and mapping of Shola forests and grasslands in the upper Nilgiri plateau and assessment of human utilization of the vegetation. Report submitted to World Wild Fund for Nature, IndiaGoogle Scholar